Furfurvylidene-lower haloalkane photosensitive composition containing arylamino disulfide

ABSTRACT

A heat-developable photographic plate comprising, on a support, a layer of a light-transmitting binder containing a furfurylidene compound, a photosensitive lower haloalkane, a brominated primary aromatic amine and an arylamino disulfide.

Umted States Patent [151 3,649,284 Price [4 Mar. 14, 1972 [54] FURFURVYLIDENE-LOWER [56] Reterenees Cited HALOALKANE PHOTOSENSITIVE COMPOSITION CONTAINING UNITED STATES PATENTS ARYLAMINQ IS L D 3,225,025 12/1965 Jeremias et al. ..260/578 X 3,342,595 9/1967 Sprague, et a1. ..96/90 1 lnventofl Lawwm Prke, 01d Owhard Beach, 3,394,395 7/1968 Mattor, etal. .96/90 Maine [73] Assignee: Scott Paper Company, Delaware County, Y Emmme" Nmla" To'chin Pa. Assistant Examiner-Won H. Louie, Jr. Attorney-John A. Weygandt, William J. Foley, John W. [22] Filed: Nov. 17, 1970 Kane, 1L and M L Faigus [21] Appl. No.: 90,433

[57] ABSTRACT 52 US. CL ..96/90, 260/571, 260/578 A hawevelopable Photographic Plate comprising, on 9 S 51 Int. Cl ..coae 1/52 port, a layer of a light-transmitting binder containing a [58] Field of Search ..96/90;260/571,578 furylidene compound, a photosensitive lower l k n a brominated primary aromatic amine and an arylamino disul- 6 Claims, No Drawings FURFURVYLIDENE-LOWER HALOALKANE PHOTOSENSITIVE COMPOSITION CONTAINING ARYLAMINO DISULFIDE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to photosensitive materials. More particularly, it relates to a negative-working, thermally developable and fixable photographic plate comprising, on a support, a light-transmitting resinous binder containing a furfurylidene compound, a brominated primary aromatic amine, a photosensitive lower haloalkane, and an arylamino disulfide.

2. History of the Prior Art In U.S. Pat. No. 3,394,395 granted July 23, 1968, there is disclosed and claimed a photographic medium comprising a transparent to translucent plastic film containing dissolved therein a furfurylidene compound as the color-forming ingredient, a primary aromatic amine enhancer, and a lower haloalkane sensitizer, e.g., iodoform. The photographic medium is negative-working and is usually carried as a film on a support, thereby forming a photographic plate. Black or colored images can be produced by the process disclosed therein by exposure of the photographic medium to light directed through an image-containing transparency. An unusual feature is that no chemical treatment is required to develop the image or to desensitize the unexposed background areas. All that is required to develop the image is to heat the medium briefly to about 100 to 150 C.

The photographic media prepared from compositions specifically described in U.S. Pat. No. 3,394,395 typically require an exposure to light for imaging such as for 10 seconds under a 7.7 kilovolt-amp carbon arc lamp at a distance of 24 inches or 5 minutes under a quartz-halogen lamp producing 9,550-foot candles at a distance of 24 inches. While such exposure intensities are low enough to be practical, it would be convenient to be able to use shorter exposure times and particularly desirable to avoid the cumbersomeness of a carbon arc lamp, i.e., to be able to use short exposure with a tungsten or mercury vapor light source.

SUMMARY OF THE INVENTION It has now been found that a heat-developable photographic plate comprising, on a support, layer of a light-transmitting binder containing a furfurylidene compound, a brominated primary aromatic amine, a photosensitive lower haloalkane and an arylamino disulfide possesses an imaging speed of from five to 50 times faster than plates specifically disclosed in said U.S. Pat. No. 3,394,395.

The arylamin disulfides of the present invention are defined by the expression H NArS-SX wherein Ar is an aryl radical and X is an alkyl, aryl, or arylamino radical.

The remaining four components of the formulation of the present invention are defined in said US. Pat. No. 3,394,395 and except insofar as primary aromatic amine is limited by brominated,"the terms used herein to describe these components are intended to have the same scope as in said patent.

DETAILED DESCRIPTION and derivatives thereof and 2,2-diaminodiphenyl disulfide HgN and derivatives thereof.

Generally the 4-aminophenyl derivatives are more active than the Z-aminophenyl and produce denser images and deeper hues. The most active compounds are 4,4- diaminodiphenyl disulfide; the alkoxy-substituted, 4,4- diaminodiphenyl disulfides, such as 3,3-dimethoxy-4,4- diaminodiphenyl disulfide, 3,3'-diethoxy-4,4-diaminodiphenyl disulfide, 2,2,5,5'-tetramethoxy-4,4'-diaminodiphenyl disulfide, and 2,2',5,5'-tetraethoxy-4,4'-diaminodiphenyl disulfide; 2,2'-diaminodiphenyl disulfide; and the alkoxy-substituted 2,2-diaminodiphenyl disulfides, such as 2,2'-diamino- 4,4-dimethoxydiphenyl disulfide, 2,2'-diamino-4,4'-diethoxydiphenyl disulfide. The inclusion of a halogen atom in the benzene ring tends to decrease the image density, as compared with the unsubstituted aminophenyl compounds, but does not substantially decrease speed. When two substituents are placed in the anilino structure, however, the disulfide frequently shows poor or no solubility in the organic solvents which dissolve the binder material of the invention. Accordingly, arylamino disulfide," as used hereinafter, is intended to comprehend those compounds soluble in the binder solution.

Even among the preferred class of compounds, there are some compounds which are insoluble in the binder solution, e.g., 2,2,5,5'-tetramethyl-4,4'-diaminodiphenyl disulfide. Others of the di-substituted anilino species are not only soluble in the binder solution, but are especially preferred for use in the present invention. Examples include 2,2',5,5'- tetramethoxy-4,4-diaminodiphenyl disulfide, and 2,2',5,5- tetraethoxy 4,4-diaminodiphenyl disulfide.

The brominated primary aromatic amines preferred for use in the present invention are the brominated m-phenylenediamines and particularly l,3-diamino-4-bromobenzene; l,3-diamino-2,6-dibromo-4-methylbenzene (2,4-diamino-3,5- dibromotoluene); l,3-diamino-2,6-dibromo-4-isopropylbenzene, and l,3-diamino-4,6-dibromobenzene.

The increase in speed described herein is achieved only through the use of both a disulfide and a brominated amine in combination with the furfurylidene compound, lower haloalkane and binder, When at least some of each amine is employed, for example 15 percent of the brominated amine based upon the total amine component, or 20 percent of the disulfide based upon the total amine component, increased speed is obtained. Optimum results are generally obtained when approximately equal parts by weight of each are employed.

In the preparation of photographic films and other photosensitive products of the invention, the furfurylidene color-former, the brominated amine, the lower haloalkane sensitizer, and the arylamino disulfide are dissolved in solvent solution along with a film-forming plastic polymer, which serves as a binder, to form a coating composition which is applied to a suitable support material. Upon drying, the coating composition becomes photosensitive. Any one of several suitable organic solvents that are volatile at room temperature or at slightly elevated temperatures such as chloroform; benzene; l,l,2-trichloroethane and methylethyl ketone can be employed as a solvent for the binder and photographic medium. Mixtures of the solvents may often result in improved solvation.

The film-forming plastic should be essentially nonreactive with the other ingredients of the solution and desirably by itself forrns a translucent or transparent film that is colorless or substantially colorless so as not to interfere with or-mask the color produced by the other ingredients in the photographic medium. Some polyester polymers have been found to be unsatisfactory presumably because the hydrogen halide, liberated through the photochemical degradation of the lower haloalkane sensitizer, attacks the ester linkage. Polymers containing large amounts of hydroxyl groups will usually interfere with image formation. In most cases, it is desirable for the polymer to form a nontacky film. Preferred polymer film-for mers or binders include polyphenylene oxide (General Electric), polysulfone, polystyrene, and polyaryl carbonate.

The weight ratio of the combined arylamino disulfide plus brominated primary aromatic amine to the furfurylidene color-former is usually in the range of 0.1:1 to 4:1 preferably 1:1 to 2:1. The weight ratio of haloalkane sensitizer to colorformer is in the range of 0.111 to 20:1, preferably 0.5:1 to 2:1. The weight ratio of resin to color-former is not too important. It will usually be in the range of 1:1 to 40:], with the lower ratios below about 5:] being preferred from the standpoint of intensity and economics. The coating compositions used are normally in the range of to weight percent solids.

A photographic plate is prepared from the coating solution by applying it to a suitable support by conventional means to produce, upon drying, a coating weight typically in the range of 3 to 15 g./m or a film thickness of l to 10 microns. Other things being equal, the thicker the film, the more intense the image. However, if the film is too thick, it is difficult to fix the background. The film thickness desired is dependent upon the vapor pressures of the amines employed and the particular resin employed.

The support used in the preparation of a photographic plate may require a coating on its surface to prevent the penetration or organic solvents, said coating being referred to hereinafter as a solvent holdup" coating. 1n the case of paper, starch, acrylic resins, polyvinyl alcohol, and similar binders will accomplish this function. In general, water soluble resins that are film-formers can be expected to give adequate solvent holdup; however, casein and other proteinaceous resins have been found to be detrimental to the photographic medium when said resins are employed in the barrier coat. In the case of transparent supports, films of polyethylene terephthalate resin (e.g., duPont's Mylar) have proved to be excellent supports and particularly suitable for the preparation of films for microphotographic copying. Materials such as cellophane are not usable except under special conditions because of the plasticizer present. Uncoated thin paper sheets, such as a carbonizing paper, can also be impregnated with the solutions to give a translucent appearing product or sheet. In cases where transparent supports are not desired, any impermeable inert support such as aluminum, sheet steel, glass, etc., may be employed.

It is known that organic halogen compounds, and particularly the lower haloalkanes, undergo photochemical reactions. The haloalkane, probably in conjunction with the primary aromatic amine, liberates a molecule of hydrogen halide, when exposed to light and heated. The hydrogen halide is believed to be an important intermediate in the chemistry of the colorformation reactions of the invention. The lower haloalkane sensitizer employed in the photographic media of the invention preferably contains 1 or 2 carbon atoms, is a solid at room temperature, and has a purity of at least 98 percent. Representative haloalkanes which have been satisfactorily employed are iodoform, carbontetrabromide and pentabromoethane.

SYNTHESIS OF ARYLAMINO DlSULFlDES Reaction scheme:

3, 3'-dlbromo-4 4'-d1- aminodlphenyl disulfide NaSGN 1. X011 N- HzN- -SCN Procedure:

To a stirred solution of 2-bromoaniline (17.2 grams, 0.10 mole) and potassium thiocyanate (29.7 grams, 0.30 mole) in 200 ml. of acetic acid cooled in an ice-bath was added dropwise a solution of bromine 16.0 grams, 0.10 mole) in acetic acid, while maintaining the temperature below 15 C. The mixture was stirred for 30 minutes, then diluted with water and the solid thiocyanate reaction-product filtered off.

The solid was stirred in 200 ml. of 10 percent KOH solution and heated on the steam-bath for 30 minutes. Then 10 ml. of 30 percent H 0 (diluted with water) was added and the heating continued for a total time of 2 hours. The yellow solid was filtered and recrystallized from ethanol-water with activated charcoal to yield pale yellow granules of the disulfide weighing 8.3 grams and having a melting point of 98l O 1 C.

2,2-diamino-4,4'-dimethoxydiphenyl disulfide OCHa Reaction scheme:

N02 NH! The 3-nitro-4-iodoanisole (20.5 grams, 0.073 mole) and Na S-9H O (53 grams, 0.22 mole) were mixed in 200 mil-1 0 and refluxed with stirring for 22 hours (or overnight). The Na S simultaneously replaces the halogen with sulfur and reduces the nitro group. The solution was cooled, filtered to remove insolubles and the filtrate heated to 60 C. To the stirred solution was added dropwise l 1 ml. of 30 percent H 0 (diluted with water) and the stirring continued for 1 hour. The oil which resulted on cooling was taken up in ethanol, and water added to yield an oily solid. Further purification gave yellow crystals weighing 1.9 grams and having a melting point of 78-80 C.

(3) IIIH: NHa

l OCHgCH: OCHgCHa 2,2-diamino5,5'-diethoxydiphenyl disulfide Reaction scheme:

N CN Part A: CH3CHgO- -NH= S omomo- CNH:

Part B:

S 011301110 L KOH O-NH 2. 11+ N lS H 1 CH3CHaO- NH:|

lTlHz NHz (BCH OH CH1OH3 Procedure: Part A To a stirred solution of p-phenetidine (13.7 grams, 0.10 mole) and NaSCN (16.2 grams, 0.20 mole) in 150 ml. acetic acid cooled in an ice-bath was added a solution of bromine (16.0 grams, 0.10 mole) in acetic acid maintaining the temperature below C. After stirring the reactants for 30 minutes, the solid reaction product was filtered off, dissolved in water and neutralized. The resulting benzothiazole was recovered by filtration. Light tan crystals resulted on recrystallization from ethanol-water using activated charcoal. The crystals weighed 5.5 grams and had a melting point of 15 8-l 60 C.

Part B The 2-amino-o-ethoxybenzothiazole (12.2 grams, 0.063 mole) was slurried in 30 ml. KOH solution (28 grams, 0.50 mole) and refluxed overnight, The reaction was diluted with water and carefully neutralized with the calculated amount of acetic acid. Vigorous foaming occurred toward the end of the neutralization. The resulting solid was filtered, dissolved in NaOH solution and refiltered to remove the insolubles. The filtrate was treated slowly with 10 ml. of 30percent H O (diluted with water). stirred for 1 hour and the resulting solid recrystallized from ethanol-water using activated charcoal. Bright yellow needles weighing 5.5 grams and having a melting point of 99- 1 0 1 C. were recovered.

Preparation of Brominated Primary Aromatic Amines The brominated primary aromatic amines may be synthesized by one of several known procedures. The following representative synthesis techniques illustrate the preparation of these compounds.

Preparation of 2,6-dibromo-4-isopropyl-m-phenylenediamine 4-isopropyl-m-phenylenediamine (30 grams; 0.2 mole) was dissolved with stirring in 100 mlv of glacial acetic acid. The stirring was continued and a solution of bromine (32 grams; 0.2 mole) in 50 ml. of glacial acetic acid was added slowly. During the addition of the bromine the reaction mixture was maintained at about room temperature with an ice-bath. Following the addition of the bromine the reaction mixture was diluted with water to precipitate the product as a crystalline solid. The solid product (l,3-diamino-b 2,6-dibromo-4- isopropyl benzene) was collected by filtration, recrystallized from chlorobenzene, and decolorized with activated charcoal. The recrystallized product was found to melt at 69.570.5 C.

Preparation of 2,6-dibromo'p-phenylenediamine p-Nitroaniline was brominated by mixing together at a temperature of 90 C. a solution of p-nitroaniline (52.2 grams) in 300 ml. of acetic acid and a solution of 128 grams of bromine in 100 ml. of acetic acid. Following the addition of the bromine, the reaction mixture was cooled, whereupon the 2,6- dibromo-4-nitroaniline intermediate precipitated as a crystalline solid. The crystals were removed by filtration and the filtrate diluted with water to induce additional crystallization of the 2,6-dibromo 4-nitroaniline.

The 2,6-dibromo-4-nitroaniline was reduced as follows: 2,6- dibromo-4-nitroaniline (60 grams) was dissolved in a mixture of calcium chloride grams), zinc (80 grams), water (75 ml.) and ethanol (200 ml). The reaction mixture was maintained at the reflux temperature for 2 hours during which time the reduction proceeded smoothly and vigorously. Following the heating period 500 ml. of ethanol was added to the hot reaction mixture, the reaction mixture brought to the boiling temperature and then filtered. Upon cooling, the product, 1,4- diamino-2,o-dibromobenzene, precipitated in the reaction mixture as a crystalline solid. The solid product was separated by filtration and recrystallized from ethanol-water (55:45). The melting point of the recrystallized 2,6-dibromo-p-phenylenediamine was 138 C.

Preparation of 4,6-dibromo-m-phenylenediamine The diacetate intermediate was prepared by stirring acetic anhydride (224 grams) into an aqueous solution of m-phenylenediamine (108 grams in 1200 ml. H 0). The reaction proceeded rapidly producing a crystalline solid product which precipitated in the reaction mixture. This product was separated by filtration and the solid diacetate product dissolved in 700 ml. of acetic acid and the resulting solution heated to C. whereupon bromine (320 grams) was added with stirring to the heated solution. Following the addition of the bromine, the reaction mixture was diluted with water whereupon the dibrominated diacetate product precipitated in the diluted mixture. The dibrominated diacetate product was then hydrolyzed as follows: a solution of potassium hydroxide (30 grams) in water (40 ml.) and ethanol (60 ml.) was warmed on the steam-bath and the dibrominated diacetate (30 grams) added thereto. After about 10 minutes of heating crystals began to appear in the hydrolysis mixture. The mixture was then chilled in an ice-bath to facilitate crystallization and filtered to remove the solid product (1,3-diamino- 4,6-dibromobenzene) which was washed, dried and found to melt at l34-l35 C.

Preparation of 2,4-diamino-3,5-dibromotoluene Sodium acetate (50 moles, 4.0 kilo) and 2,4- toluenediamine (50 moles, 6.1 kilo) were dissolved in 35 liters of 84 percent acetic acid with stirring and cooling. When the solution reached 20 C. bromine (70 moles, 11.3 kilo) was added over a period of45 minutes. As the temperature started to rise, ice chips were added to maintain the temperature below 25 C. When the bromine addition was complete the reaction mixture was filtered immediately and the product washed well with water to yield 7.0 kilos of dark product. The product (l,3-diamino-2,6-dibromo-4-methyl-benzene) was recrystallized from acetone/water using activated charcoal to yield off-white plates, which melted at 143.5 C. with violent decomposition.

The furfurylidene compound preferably comprises a furan derivative corresponding to one of the formulae:

(II) O-CH X wherein n is 1 or 2, with X, when n is 1, being a hydroxyl, amino, phenyl, or naphthyl radical, and when n is 2, being absent or a phenylene, naphthylene or 4,4-biphenylene radical; and X is a methyl, nitro, or furfurylidene imine radical or a carbon atom forming a part of a cyclic acetal ring with the other X to give a difurfurylidene pentaerythritol.

The furfurylidene color-former is usually prepared by reacting furfural with a suitable amine, in the case of the furfurylidene imines, and with a suitable glycol or higher polyol, in the case of the cyclic acetals. Conventional, well understood organic synthesis techniques are used. The reaction is usually a condensation reaction carried out with an acidic catalyst in an organic solvent at temperatures in the range of 80 to 120 C. It is preferred to use furfurylidene compounds in the photographic medium that are crystalline solids at room temperature and have melting points in the range of 70 to 225 C., but liquid furfurylidene compounds which boil between and 220 C. at 10 mm. Hg pressure can also be used. Particularly preferred are difuryfurylidene pentaerythritol and difurfurylidene azine.

it is important to thoroughly purify the furfurylidene after its preparation in order to rid it of dark color bodies and reaction tars that would unduly tone or destroy the clarity of the background areas of the photographic medium.

After the reaction product is purified, it is admixed with a solvent and the other ingredients of the photographic medium to prepare a coating solution. The coating solution is applied to a suitable support such as coated paper and dried to leave the photographic medium in the form of a film which upon drying becomes photosensitive. A print is made by exposing the film to light through a transparent original, followed by heating of the exposed plate to a temperature greater than 100 C. to develop the image.

These and other principles, features and advantages of the present invention will become more fully understood from a consideration of the following specific examplesv EXAMPLE I A photographic plate was prepared from a coating solution comprising:

Component Parts by Weight difurfurylidene pentaery thritol pentaery l .0

2,2,5 '-tetrarnethoxy-4.4'

diarninodiphenyl disulfide 2,4 diamino,3 5-dibromotoluene LO iodoform 2.0

polystyrene (Dow Chemical's Styron 5666B) 10.0 chloroform 150 The solution was applied by means of a No. Mayer rod to one side of a paper sheet provided with a solvent holdup coating and air-dried. The plate was exposed through a negative transparency-a Stauffer 2 l-step wedgefor seconds with 9,550-foot candles of light from a quartz-halogen lamp at a distance of 24 inches. Heat development at 138 C. for 1 minute produced a l5-step image of an intense gray color.

EXAMPLE I] A coating solution comprising:

Component Parts by Weight dil'urfurylidene pentaerythritol 4 .6-dibromom-phenylenediamine 1.0 4.4'-diaminodiphenyl disulfide LO iodoform 2.6

polystyrene (Styron 56661.) 16.0 chloroform 44 EXAMPLE lll An equal amount by weight of polysulfone (Union Carbides P 1700) was substituted for the polystyrene of the formulation of Example ll. A plate prepared from the resultant coating produced identical results.

EXAMPLE IV To the formulation of Example II was added 1.0 part by weight of 2,4-toluene diamine. A plate prepared from the resultant coating solution produced a dense blue image after exposure and development as in Example ll.

EXAMPLE v A coating solution comprising:

Component Parts by Weight dil'urfurylidenepentaerythritol Z v i-diam ino3 .S-dibromotoluene 2,2 -diaminodiphen vl disttlflde iodoforrn 2.0

polystyrene (Styron 5666b) l4 chloroform l26 was applied by means of an No. 20 Mayer rod to one side of a paper base provided with a solvent holdup coating and airdried. The resulting sheet was exposed through a transparent original for 20 seconds with 9,550-foot candles of light from a quartz-halogen lamp at a distance of 24 inches. Heat development at 127 C. for 1 minute produced a dense brown image, which was stable in the presence of light and showed no loss of density after 1 hour of exposure to a carbon arc lamp at a distance of 8 inches.

EXAMPLE VI The substitution of polyphenylene oxide for polystyrene in Example V produced no change.

EXAMPLE VII Anequal weight of 3,3'-dimethoxy-4,4'-diaminodiphenyl disulfide was substituted for the 2,2-diaminodiphenyl disulfide in the formulation of Example V. An exposure of 30 seconds under the same light source and development at 138 C. for 1 minute produced a blue-black image.

Example Vlll A coating solution comprising:

Component Parts by Weight difurfurylidene pentaeryrhritol 4 4-diaminodiphenyi disulfide 1.0 2,4-diamino-3,5-dibromotoluene 1.0 iodoform 2.0

pol yphenylene oxide methylenechlorideltrichloro ethylene 60/40 146 was coated and exposed as in Example 1, giving an l8-step imate of purple color.

EXAMPLE lX The substitution of an equal amount of polysulfone for the polyphenylene oxide of Example VIII produced substantially no change in results.

EXAMPLE X Substitution of an equal amount of difurfurylidene azine for the furan of Example Vlll produced a l2-step imate upon exposure and development.

While the invention has been described with reference to preferred embodiments thereof, it is understood that various other changes and modifications thereof will occur to a person of ordinary skill in the art without departing from the spirit and scope of the invention, as defined by the appended claims.

What is claimed is:

1. A heat-developable photographic plate comprising, on a support, a layer of a light-transmitting resinous binder containing a furfurylidene compound, a photosensitive lower haloalltane, a brominated primary aromatic amine and an arylamino disulfide according to the formula H NArS-SX wherein Ar is an aryl radical and X is an arylamino radical.

2. The plate according to claim 1 wherein the arylamino disulfide is a 4,4'-diaminodiphenyl disulfide.

3. The plate according to claim 1 wherein the disulfide is an alkoxy-substituted 4,4'-diaminodiphenyl disulfide.

4. The plate according to claim 1 wherein the arylamino 5 disulfide is a 2,2'-diaminodiphenyl disulfide. 

2. The plate according to claim 1 wherein the arylamino disulfide is a 4,4''-diaminodiphenyl disulfide.
 3. The plate according to claim 1 wherein the disulfide is an alkoxy-substituted 4,4''-diaminodiphenyl disulfide.
 4. The plate according to claim 1 wherein the arylamino disulfide is a 2,2''-diaminodiphenyl disulfide.
 5. The plate according to claim 1 wherein the disulfide is an alkoxy-substituted 2,2''-diaminodiphenyl disulfide.
 6. The plate according to claim 1 wherein the brominated amine is a brominated m-phenylenediamine. 